Salivary binding proteins

Salivary Binding Proteins. Salivary proteins that bind to hydroxyapatite and which may be important in pellicle formation include,(2 ) (i) mucous glycoproteins (MW=3-5... 

Table 3.1 Odourant Binding Proteins N-terminai sequences of various mammalian urinary and nasal lipocalyins — correspondence/homology with pig salivary protein, pig-SAL (Id <60%) (from Pelosi, 1998).

Laukaitis C.M., Critser E.S. and Karin R.C. (1997). Salivary androgen-binding protein (ABP) mediates sexual isolation in Mus musculus. Evolution 51, 2000-2005. 

Dietz, B. A., Hagerman, A. E., and Barrett, G. W. (1994). Role of condensed tannin on salivary tannin-binding proteins, bioenergetics and nitrogen digestibility in Micro-tuspennsylvanicus. Journal of Mammalogy 75,880-889. 

Mans, B.J. et al. (2007) The crystal structure of D7r4, a salivary biogenic amine-binding protein from the malaria mosquito anopheles gambiae. J. Biol. Chem., 282 (50), 36626-36633. 

Juntheikki, M.R., JulkunenTiitto, R., and Hagerman, A.E., Salivary tannin-binding proteins in root vole (Microtus oeconomus Pallas), Biochem. Syst. Ecol., 24, 25, 1996. 

The third class of extracellular calcium binding proteins are the salivary acidic proline-rich proteins. The major proteins have been named salivary proteins A and C. These proteins bind to and inhibit the formation of hydroxylapatite and it has been suggested that they function to aid in the maintenance of the integrity of the teeth. Calcium is bound by the salivary proteins by a series of negatively charged phosphoserine residues. Treatment with phosphatases to selectively remove the phosphoryl-moieties from phosphoserine dramatically reduces calcium binding affinity. 

Bennick A The binding of calcium to a salivary phosphoprotein, protein C, and comparison with calcium binding to protein A, a related salivary phosphoprotein. Biochem J 1977 163 241-245. Hay DI, Moreno EC, Schlesinger DH Phosphoprotein inhibitors of calcium phosphate precipitation from salivary secretion. Inog Persp Biol Med 1979 2 271-285. 

Many foods obtained from plants contain tannins. These are phenolic compounds that bind proteins, such as mammalian enzymes. It has been shown in vitro that tannic acid significantly reduces the lubricating qualities of human saliva both by decreasing its viscosity and increasing friction [55], This effect depends on the presence of salivary PRPs, which have a high affinity for tannins [56], It has been shown that the introduction of tannins into the diet can stimulate the production of PRPs in the saliva of rats [57], PRPs are a major component of salivary pellicle, and thus it would not be surprising to find that dietary tannins affect the viscosity of pellicle. 

On the ingestion of a physiologic quantity of cobalamin, a series of specific events occur in a sequential fashion to ensure appropriate and adequate absorption. First, cobalamin is released from dietary proteins, whereon the salivary R proteins ensure intragastric binding of the substance. Thereafter, intraduodenal digestion of the R protein cobalamin complexes occurs, particularly by pancreatic proteases, which are responsible for the release of cobalamin. Once cobalamin is free within the duodenum or upper small bowel, binding of the vitamin by intrinsic factor occurs before its transport to the lower ileum. At this point, the intrinsic factor-bound cobalamin is attached to the apical membrane of the ileum cells, and absorption via specific receptor-mediated pathways occurs. The transcellular transport of cobalamin in the ileal mucosa is a slow process and presumably involves endocytosis. The vitamin is thereafter released into the portal circulation and passes to the liver for processing. 

Additional histamine-binding proteins were putatively identified by characterization of cDNAs prepared from mRNAs of salivary glands of /. scapularis (5(f) and Amblyomma americanum (51). As genomic and proteomic studies of tick salivary glands progress additional molecules that modulate these important mediators will certainly be described. 

Another exciting development has been the discovery of a nitric oxide binding protein in the salivary gland of the blood-sucking bug Rhodnius prolixus (23). This protein has unusual binding properties that are different than those of the related protein found in humans, and comparative analysis of the differences in structure of the human vs. bug proteins should generate testable hypotheses on the structure-function properties of the natural human protein. 

Ribeiro, J.M., Hazzard, J.M., Nussenzverg, R.H., Champagne, D.E., Walker, F.A.. 1993. Reversible binding of nitric oxide by a salivary heme protein from a bloodsucking insect. Science 260 539-541. 

Both proteinaceous and non-proteinaceous analogs have been studied. Examples include a synthetic 20 amino acid adhesin peptide sequence copied from S. mutans and LTA of groups A and B streptococci. The synthetic peptide mimics a S. mutans adhesin that binds a salivary protein on dental surfaces and was shovm to inhibit bacterial adherence to immobilized salivary receptors in vitro. In vivo, this peptide hindered the recolonization by S. mutans on teeth that had been cleared of the... 

Sulfation has also been documented in salivary proteins, specifically statherin. The enzymes in saliva are the first wave of the human digestion process and statherin prevents the precipitation of calcium phosphate in the salivary gland and saliva. Since TPST is secreted along with statherin, sulfation plays a role in digestion by binding hydroxylapatite and preventing its precipitation. 

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